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I. El-Hussain | Sultan Qaboos University - Academia.edu

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I. El-Hussain

Sultan Qaboos University, Earthqake Monitoring Center, Faculty Member

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Armando Marques-Guedes

UNL - New University of Lisbon

Iolanda Craifaleanu

Technical University Of Civil Engineering, Bucharest

Istanbul Technical University

Hacettepe University

Fabián Hoyos Patiño

Universidad Nacional de Colombia (National University of Colombia)

King Saud University

Fusun Balik Sanli

Yildiz Technical University

Consiglio Nazionale delle Ricerche (CNR)

King Saud University

Università degli Studi "La Sapienza" di Roma

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Papers by I. El-Hussain

Incremental dynamic analysis of a hospital building in Oman

CRC Press eBooks, Aug 23, 2022

Probabilistic tsunami hazard assessment along Oman coast from submarine earthquakes in the Makran subduction zone

Arabian Journal of Geosciences, 2016

The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two con... more The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two confirmed tsunamis during the twentieth and twenty-first centuries: the 1945 tsunami due to an earthquake in the Makran subduction zone in the Sea of Oman (near-regional field tsunami) and the Indian Ocean tsunami in 2004, caused by an earthquake from the Andaman Sumatra subduction zone (far-field tsunami). In this paper, we present a probabilistic tsunami hazard assessment for the entire coast of Oman from tectonic sources generated along the Makran subduction zone. The tsunami hazard is assessed taking into account the contribution of small-and large-event magnitudes. Results of the earthquake recurrence rate studies and the tsunami numerical modeling for different magnitudes were used through a logic-tree to estimate the tsunami hazard probabilities. We derive probability hazard exceedance maps for the Omani coast considering the exposure times of 100, 250, 500, and 1000 years. The hazard maps consist of computing the likelihood that tsunami waves exceed a specific amplitude. We find that the probability that a maximum wave amplitude exceeds 1 m somewhere along the coast of Oman reaches, respectively, 0.7 and 0.85 for 100 and 250 exposure times, and it is up to 1 for 500 and 1000 years of exposure times. These probability values decrease significantly toward the southern coast of Oman where the tsunami impact, from the earthquakes generated at Makran subduction zone, is low.

Development of ground-shaking maps for the Sultanate of Oman

Natural Hazards, 2016

This study presents research toward the development of ground-shaking maps after a real earthquak... more This study presents research toward the development of ground-shaking maps after a real earthquake, or for scenario earthquakes originating from seismic sources within and around the Sultanate of Oman. Major important earthquake sources that are important for the Sultanate of Oman are the Makran zone, the Zagros zone, the Zendan-Minab system, the Oman Mountain zone, the Owen fracture zone and the Gulf of Aden zone. The earthquakes that take place on these zones, particularly those from Makran, already resulted and are likely to result in ground-shaking levels that may be significant for the

Monitoring Microseismicity in a Carbonate Oil Field, North Oman

Microseismicity was monitored continuously for 2003 and 2004 years using shallow downhole seismic... more Microseismicity was monitored continuously for 2003 and 2004 years using shallow downhole seismic network in a carbonate oil field in Northern Oman. A total of 406 microearthquake events were analyzed to assess events location relative to producing horizons. The depth of the microearthquakes ranges from 0 to 2.95 km below the ground surface. The events location is confined to the

Probabilistic seismic hazard maps for the sultanate of Oman

Natural Hazards, 2012

This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in th... more This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in the framework of logic tree for Oman. The earthquake catalogue was homogenized, declustered, and used to define seismotectonic source model that characterizes the seismicity of Oman. Two seismic source models were used in the current study; the first consists of 26 seismic source zones, while the second is expressing the alternative view that seismicity is uniform along the entire Makran and Zagros zones. The recurrence parameters for all the seismogenic zones were determined using the doubly bounded exponential distribution except the zones of Makran, which were modelled using the characteristic distribution. Maximum earthquakes were determined and the horizontal ground accelerations in terms of geometric mean were calculated using ground-motion prediction relationships developed based upon seismic data obtained from active tectonic environments similar to those surrounding Oman. The alternative seismotectonic source models, maximum magnitude, and ground-motion prediction relationships were weighted and used to account for the epistemic uncertainty. Hazard maps at rock sites were produced for 5 % damped spectral acceleration (SA) values at 0.1, 0.2, 0.3, 1.0 and 2.0 s spectral periods as well as peak ground acceleration (PGA) for return periods of 475 and 2,475 years. The highest hazard is found in Khasab City with maximum SA at 0.2 s spectral period reaching 243 and 397 cm/s 2 for return periods 475 and 2,475 years,

Deterministic seismic hazard assessment for Sultanate of Oman

Arabian Journal of Geosciences, 2012

The Sultanate of Oman forms the southeastern part of the Arabian plate, which is surrounded by re... more The Sultanate of Oman forms the southeastern part of the Arabian plate, which is surrounded by relatively high active tectonic zones. Studies of seismic risk assessment in Oman have been an important ongoing socioeconomic concern. Using the results of the seismic hazard assessment to improve building design and construction is an effective way to reduce the seismic risk. In the current study, seismic hazard assessment for the Sultanate of Oman is performed through the deterministic approach with particular attention on the uncertainty analysis applying a recently developed method. The input data set contains a defined seismotectonic model consisting of 26 seismic zones, maximum magnitudes, and 6 alternative ground motion prediction equations that were used in four different tectonic environments: obduction zone earthquake (Zagros fold thrust belt), subduction zone earthquakes (Makran subduction zones), normal and strike-slip transform earthquakes (Owen and Gulf of Aden zones), and stable craton seismicity (Arabian stable craton). This input data set yielded a total of 76 scenarios at each point of interest. A 10 % probability that any of the 76 scenarios may exceed the largest median ground acceleration is selected. The deterministic seismic hazards in terms of PGA, 5 % damped spectral acceleration at 0.1, 0.2, 1.0 and 2.0 s are performed at 254 selected points. The ground motion was calculated at the 50th and 84th percentile levels for selected probability of exceeding the median value. The largest ground motion in the Sultanate of Oman is observed in the northeastern part of the country.

Efficiency of horizontal-to-vertical spectral ratio (HVSR) in defining the fundamental frequency in Muscat Region, Sultanate of Oman: a comparative study

Arabian Journal of Geosciences, 2013

Site investigation studies provide the basic soil and engineering properties, which usually deter... more Site investigation studies provide the basic soil and engineering properties, which usually determined using many investigations as standard penetration test, cone penetration test, and multichannel analysis of surface wave (MASW), to identify and evaluate a potential hazard. The horizontal to vertical spectral ratio (HVSR) analysis method is a tool based on the spectral analyses of recorded ambient noise; it is widely used to estimate site effect parameters (fundamental frequency and the associated soil amplification), and many surveys using this technique to study the site effect have provided convincing results. Saqqara pyramid lies to the southwest of Cairo near the epicenter of Cairo earthquake that happened on 12 October 1992. The pyramid is severely damaged by the earthquake with epicenter at about 14 km away; as a result, numerous efforts are exerted to restore the pyramid and to prevent it from total collapse. The current work is motivated by such efforts with focus on the potentiality of using the spectral ratio method (HVSR) to define subsurface monuments. The microtremor measurements were performed at 15 sites distributed in front of the southern side of the Zoser pyramid region in order to calculate the HVSR. Array shape and dimensions is chosen based on the prior information about the location and extension of the tunnel underneath. The tunnel extended about 20 m underneath the area adjacent to the southern gate of the pyramid. The amplification spectra have been evaluated for the soil column at each site location, and the fundamental frequency obtained and peak amplitudes are contoured showing some low value trends at the area adjacent to the southern gate. This may lead to the possibilities of the HVSR method to explore the subsurface monuments. However, this statement is still in the early stage and further theoretical investigation is required.

Seismic microzonation for Muscat region, Sultanate of Oman

Natural Hazards, 2013

Site characterization was carried out for Muscat region using the ambient noise measurements appl... more Site characterization was carried out for Muscat region using the ambient noise measurements applying the horizontal-to-vertical spectral ratio (HVSR) technique and using active seismic survey utilizing the multichannel analysis of surface waves (MASW) of survey data. Microtremors measurements were carried out at 459 sites using shortperiod sensors. This extensive survey allowed the fundamental resonance frequency of the soft soil to be mapped and areas prone to site amplification to be identified. The results indicate a progressive decrease in the fundamental resonance frequencies from the southern and eastern parts, where the bedrock outcrops, toward the northern coast where a thickness of sedimentary cover is present. Shear wave velocity (Vs) was evaluated using the 2-D MASW at carefully selected 99 representative sites in Muscat. These 99 sites were investigated with survey lines of 52 m length. 1-D and interpolated 2-D profiles were generated up to a depth range 20-40 m. The vertical Vs soundings were used in the SHAKE91 software in combination with suitable seismic input strong motion records to obtain the soil effect. Most of the study area has amplification values less than 2.0 for all

Comparison of Oman Seismic Code for Buildings with International Counterparts

The paper presents a comparison of the recently developed Oman Seismic Code (OSC) for buildings w... more The paper presents a comparison of the recently developed Oman Seismic Code (OSC) for buildings with Uniform Building Code 1997 (UBC) and International Building Code 2006 (IBC). OSC utilizes the seismic hazard assessment of the country and is applicable to building heights up to 60 m. OSC categorizes Sultanate of Oman into two zones; a high seismic zone (Zone-1) and a low seismic zone (Zone-2). Muscat the capital of the country falls in Zone-1. According to UBC, Muscat falls in Zone-2A, this definition was used as the reference for zonal equivalence. The paper compares base shear and lateral force distribution obtained from the three seismic codes using equivalent static load method. 4-, 10and 14storey buildings having heights of 17 m, 41 m and 57 m, respectively were considered. The buildings were modeled as reinforced concrete having normal occupancy conditions, resting on soil class “C” defined as very dense soil or soft rock. Both zones of OSC were used for comparison. For all b...

Application of NEHRP classification to AVS30 obtained from microtremor array measurement in Muscat, Oman

Seismic Liquefaction Potential in Muscat, Sultanate of Oman

Journal of Earth Science & Climatic Change

Seismic liquefaction is a serious geotechnical engineering problem that takes place in saturated ... more Seismic liquefaction is a serious geotechnical engineering problem that takes place in saturated cohesion less soils during earthquakes due to the increase of pore-pressure so that the soil shear strength is decreased to zero. Muscat is situated in the north-eastern part of Oman close to Oman Mountains, which witnessed four earthquakes of order of 5.2 magnitude in the last 1300 years. The surface geology of Muscat reveals great variety of hard rocks in the eastern, southern and western parts to dense and lose sediments in the middle and northern parts. Muscat Municipality provided 1082 borehole data to be examined for their liquefaction susceptibility based on the soil characteristics. Susceptible soils only are further considered to liquefaction hazard assessment. Liquefaction occurs during an earthquake if the cyclic stress ratio (CSR) caused by the earthquake is higher than the cyclic resistance ratio (CRR) of the soil. CSR values were evaluated using probabilistic peak ground acceleration (PGA) values for return period of 2475 years at the surface given by detailed hazard and micro zonation studies. CRR for Muscat region is conducted based on the borehole data with N values of SPT tests, and shear wave velocity results from 99 MASW surveys over the entire region. All the required corrections to get standardized (N1) 60 values, to correct shear-wave velocity, and scale the results for Mw 6.0 instead of the proposed 7.5 are conducted. Liquefaction hazard maps were created using the minimum factor of safety (FS) at each site as a representative of the FS against liquefaction at that location. Results indicate that under the current level of seismic hazard, liquefaction potential is possible at some sites along the northern coast, where alluvial soils, shallow ground water table, and relatively high ground motion are present. The expected settlement of the soft soil at each liquefiable site is also evaluated.

Moment Magnitudes of Local/Regional Events from 1D Coda Calibrations in the Broader Middle East Region

Bulletin of the Seismological Society of America, 2016

Short-period body wave and long-period surface wave magnitudes are important for event characteri... more Short-period body wave and long-period surface wave magnitudes are important for event characterization, and yield estimation applications. However, the uneven distribution of stations, complex heterogeneous structure, and high attenuation of the Middle East make it difficult to calculate these magnitudes using simple 1-D path corrections. While reliable 1-D long-period regional moment magnitudes are routinely computed for the larger magnitude events, oftentimes the smaller events do not have the required bandwidth and are thus not suitable for long-period waveform modeling that require periods of 5 seconds or greater. The complex structure of the lithosphere in the region causes significant variation in the recorded amplitude of body and surface waves that travel along different paths, as well as phase blockage. These strong 2-D effects are most significant for source characterization of small and moderate magnitude events, which are often only observable at periods of less than 2 seconds. While the regional coda envelope method for moment magnitude estimation [22] has proven to be very robust in many studies, they still require 2-D path corrections for the shorter periods in laterally complex regions Iranian and Turkish Plateaus. This current study will provide the necessary 1-D initial starting model for use in a future 2-D coda study. We are also very fortunate to have access to many new broadband stations that have become available in the region, through improved national networks as well as temporary deployments. This has given us the opportunity to make thousands of coda amplitude measurements to calculate source parameters, specifically we have estimated the source moment-rate spectra and moment magnitudes for roughly 2,900 events recorded by 74 stations over 13 narrow frequency bands ranging between 0.03-8 Hz. Moreover, this data will be crucial for 2-D path corrections for coda in the future. The absolute scaling of these spectra was calculated based on an independent waveform modeling solutions of the moment magnitudes for a subset of these events to avoid circularity. Using our1-D path calibrations, we obtain fairly good agreement with waveform-modeled seismic moments for the larger events (Mw > 4.5), for the low frequencies (< 0.7 Hz). As expected, the coda-derived source spectra become very scattered at higher frequencies (>0.7-Hz) because of uncorrected 2-D path effects as well as mixing of both Sn-coda and Lg-coda which are likely to have different attenuation.

Site-specific earthquake ground motion parameters at the southeastern part of Muscat, Sultanate of Oman

Journal of African Earth Sciences

Abstract The site-specific earthquake ground motion parameters were presented for the southeaster... more Abstract The site-specific earthquake ground motion parameters were presented for the southeastern part of Muscat governorate, including amplification factor at different periods and the values of PGA and spectral accelerations at the surface. The study starts with assessment of the seismic hazard at bedrock level using the probabilistic approach. This assessment was preformed considering an updated earthquake catalogue . The outputs of the probabilistic seismic hazard were uniform hazard spectra for return periods of 475,975 and 2475 years. Spectral matching technique was applied to define the compatible ground motion time series based on the outputs of the probabilistic approach and the deaggregation process. The representative's dynamic soil profiles were determined using the in-situ measurements of compressional and shear waves. The effects of soil deposits on the propagated ground motions time series was evaluated using the equivalent linear analysis in the frequency domain. The final results clarified that, the fundamental site period at the middle coastal parts of the area has the largest values (0.2–0.276 s). The maximum amplification factors found to be 2.76, 2.36, and 2.8 for the periods of PGA, 0.1 s, and 0.2 s, respectively. The values of PGA and spectral accelerations at the surface level are also provided.

Compiling an earthquake catalogue for the Arabian Plate, Western Asia

Journal of Asian Earth Sciences

Integrated GPR, ERT and MASW for detecting near‐surface caverns at Duqm area, Sultanate of Oman

Near Surface Geophysics

Probabilistic and deterministic estimates of near-field tsunami hazards in northeast Oman

Geoscience Letters

Tsunamis generated along the Makran subduction zone (MSZ) threaten the Sur coast of Oman, accordi... more Tsunamis generated along the Makran subduction zone (MSZ) threaten the Sur coast of Oman, according to deterministic and probabilistic analyses presented here. A validated shallow water numerical code simulates the sourceto-coast propagation and quantifies the coastal hazard in terms of maximum water level, flow depth, and inundation distance. The worst-case source assumed for the eastern MSZ is a thrust earthquake of Mw 8.8. This deterministic scenario produces simulated wave heights reaching 2.5 m on the Sur coast leading to limited coastal inundation extent. Because Oman adjoins the western MSZ, the probabilistic analysis includes the effect of this segment also. The probabilistic analysis shows onshore inundations exceeding 0.4 km northwest of Sur where flow depths are likely to exceed 1 m in 500 years. Probability analysis shows lesser inundation areas with probability of exceeding 1 m flow depth up to 80% in 500-year exposure time. Teletsunamis are excluded from these analyses because far-field waves of the 2004 Indian Ocean tsunami did not impact the Sur coast. Also excluded for simplicity are tsunamis generated by submarine slides within or near MSZ rupture areas. The results of this research provide essential information for coastal planning, engineering and management in terms of tsunami hazard and an essential step toward tsunami risk reductions in the northwest Indian Ocean.

Probabilistic Seismic Hazard Assessment for the Arabian Peninsula

Pure and Applied Geophysics

Developing a seismic source model for the Arabian Plate

Arabian Journal of Geosciences

Near-surface site characterization at Quriyat City, Sultanate of Oman using HVSR and MASW techniques

Arabian Journal of Geosciences, 2015

COOL: Crust of the Oman Ophiolite and its Lithosphere-a passive seismic experiment

Incremental dynamic analysis of a hospital building in Oman

CRC Press eBooks, Aug 23, 2022

Probabilistic tsunami hazard assessment along Oman coast from submarine earthquakes in the Makran subduction zone

Arabian Journal of Geosciences, 2016

The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two con... more The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two confirmed tsunamis during the twentieth and twenty-first centuries: the 1945 tsunami due to an earthquake in the Makran subduction zone in the Sea of Oman (near-regional field tsunami) and the Indian Ocean tsunami in 2004, caused by an earthquake from the Andaman Sumatra subduction zone (far-field tsunami). In this paper, we present a probabilistic tsunami hazard assessment for the entire coast of Oman from tectonic sources generated along the Makran subduction zone. The tsunami hazard is assessed taking into account the contribution of small-and large-event magnitudes. Results of the earthquake recurrence rate studies and the tsunami numerical modeling for different magnitudes were used through a logic-tree to estimate the tsunami hazard probabilities. We derive probability hazard exceedance maps for the Omani coast considering the exposure times of 100, 250, 500, and 1000 years. The hazard maps consist of computing the likelihood that tsunami waves exceed a specific amplitude. We find that the probability that a maximum wave amplitude exceeds 1 m somewhere along the coast of Oman reaches, respectively, 0.7 and 0.85 for 100 and 250 exposure times, and it is up to 1 for 500 and 1000 years of exposure times. These probability values decrease significantly toward the southern coast of Oman where the tsunami impact, from the earthquakes generated at Makran subduction zone, is low.

Development of ground-shaking maps for the Sultanate of Oman

Natural Hazards, 2016

This study presents research toward the development of ground-shaking maps after a real earthquak... more This study presents research toward the development of ground-shaking maps after a real earthquake, or for scenario earthquakes originating from seismic sources within and around the Sultanate of Oman. Major important earthquake sources that are important for the Sultanate of Oman are the Makran zone, the Zagros zone, the Zendan-Minab system, the Oman Mountain zone, the Owen fracture zone and the Gulf of Aden zone. The earthquakes that take place on these zones, particularly those from Makran, already resulted and are likely to result in ground-shaking levels that may be significant for the

Monitoring Microseismicity in a Carbonate Oil Field, North Oman

Microseismicity was monitored continuously for 2003 and 2004 years using shallow downhole seismic... more Microseismicity was monitored continuously for 2003 and 2004 years using shallow downhole seismic network in a carbonate oil field in Northern Oman. A total of 406 microearthquake events were analyzed to assess events location relative to producing horizons. The depth of the microearthquakes ranges from 0 to 2.95 km below the ground surface. The events location is confined to the

Probabilistic seismic hazard maps for the sultanate of Oman

Natural Hazards, 2012

This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in th... more This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in the framework of logic tree for Oman. The earthquake catalogue was homogenized, declustered, and used to define seismotectonic source model that characterizes the seismicity of Oman. Two seismic source models were used in the current study; the first consists of 26 seismic source zones, while the second is expressing the alternative view that seismicity is uniform along the entire Makran and Zagros zones. The recurrence parameters for all the seismogenic zones were determined using the doubly bounded exponential distribution except the zones of Makran, which were modelled using the characteristic distribution. Maximum earthquakes were determined and the horizontal ground accelerations in terms of geometric mean were calculated using ground-motion prediction relationships developed based upon seismic data obtained from active tectonic environments similar to those surrounding Oman. The alternative seismotectonic source models, maximum magnitude, and ground-motion prediction relationships were weighted and used to account for the epistemic uncertainty. Hazard maps at rock sites were produced for 5 % damped spectral acceleration (SA) values at 0.1, 0.2, 0.3, 1.0 and 2.0 s spectral periods as well as peak ground acceleration (PGA) for return periods of 475 and 2,475 years. The highest hazard is found in Khasab City with maximum SA at 0.2 s spectral period reaching 243 and 397 cm/s 2 for return periods 475 and 2,475 years,

Deterministic seismic hazard assessment for Sultanate of Oman

Arabian Journal of Geosciences, 2012

The Sultanate of Oman forms the southeastern part of the Arabian plate, which is surrounded by re... more The Sultanate of Oman forms the southeastern part of the Arabian plate, which is surrounded by relatively high active tectonic zones. Studies of seismic risk assessment in Oman have been an important ongoing socioeconomic concern. Using the results of the seismic hazard assessment to improve building design and construction is an effective way to reduce the seismic risk. In the current study, seismic hazard assessment for the Sultanate of Oman is performed through the deterministic approach with particular attention on the uncertainty analysis applying a recently developed method. The input data set contains a defined seismotectonic model consisting of 26 seismic zones, maximum magnitudes, and 6 alternative ground motion prediction equations that were used in four different tectonic environments: obduction zone earthquake (Zagros fold thrust belt), subduction zone earthquakes (Makran subduction zones), normal and strike-slip transform earthquakes (Owen and Gulf of Aden zones), and stable craton seismicity (Arabian stable craton). This input data set yielded a total of 76 scenarios at each point of interest. A 10 % probability that any of the 76 scenarios may exceed the largest median ground acceleration is selected. The deterministic seismic hazards in terms of PGA, 5 % damped spectral acceleration at 0.1, 0.2, 1.0 and 2.0 s are performed at 254 selected points. The ground motion was calculated at the 50th and 84th percentile levels for selected probability of exceeding the median value. The largest ground motion in the Sultanate of Oman is observed in the northeastern part of the country.

Efficiency of horizontal-to-vertical spectral ratio (HVSR) in defining the fundamental frequency in Muscat Region, Sultanate of Oman: a comparative study

Arabian Journal of Geosciences, 2013

Site investigation studies provide the basic soil and engineering properties, which usually deter... more Site investigation studies provide the basic soil and engineering properties, which usually determined using many investigations as standard penetration test, cone penetration test, and multichannel analysis of surface wave (MASW), to identify and evaluate a potential hazard. The horizontal to vertical spectral ratio (HVSR) analysis method is a tool based on the spectral analyses of recorded ambient noise; it is widely used to estimate site effect parameters (fundamental frequency and the associated soil amplification), and many surveys using this technique to study the site effect have provided convincing results. Saqqara pyramid lies to the southwest of Cairo near the epicenter of Cairo earthquake that happened on 12 October 1992. The pyramid is severely damaged by the earthquake with epicenter at about 14 km away; as a result, numerous efforts are exerted to restore the pyramid and to prevent it from total collapse. The current work is motivated by such efforts with focus on the potentiality of using the spectral ratio method (HVSR) to define subsurface monuments. The microtremor measurements were performed at 15 sites distributed in front of the southern side of the Zoser pyramid region in order to calculate the HVSR. Array shape and dimensions is chosen based on the prior information about the location and extension of the tunnel underneath. The tunnel extended about 20 m underneath the area adjacent to the southern gate of the pyramid. The amplification spectra have been evaluated for the soil column at each site location, and the fundamental frequency obtained and peak amplitudes are contoured showing some low value trends at the area adjacent to the southern gate. This may lead to the possibilities of the HVSR method to explore the subsurface monuments. However, this statement is still in the early stage and further theoretical investigation is required.

Seismic microzonation for Muscat region, Sultanate of Oman

Natural Hazards, 2013

Site characterization was carried out for Muscat region using the ambient noise measurements appl... more Site characterization was carried out for Muscat region using the ambient noise measurements applying the horizontal-to-vertical spectral ratio (HVSR) technique and using active seismic survey utilizing the multichannel analysis of surface waves (MASW) of survey data. Microtremors measurements were carried out at 459 sites using shortperiod sensors. This extensive survey allowed the fundamental resonance frequency of the soft soil to be mapped and areas prone to site amplification to be identified. The results indicate a progressive decrease in the fundamental resonance frequencies from the southern and eastern parts, where the bedrock outcrops, toward the northern coast where a thickness of sedimentary cover is present. Shear wave velocity (Vs) was evaluated using the 2-D MASW at carefully selected 99 representative sites in Muscat. These 99 sites were investigated with survey lines of 52 m length. 1-D and interpolated 2-D profiles were generated up to a depth range 20-40 m. The vertical Vs soundings were used in the SHAKE91 software in combination with suitable seismic input strong motion records to obtain the soil effect. Most of the study area has amplification values less than 2.0 for all

Comparison of Oman Seismic Code for Buildings with International Counterparts

The paper presents a comparison of the recently developed Oman Seismic Code (OSC) for buildings w... more The paper presents a comparison of the recently developed Oman Seismic Code (OSC) for buildings with Uniform Building Code 1997 (UBC) and International Building Code 2006 (IBC). OSC utilizes the seismic hazard assessment of the country and is applicable to building heights up to 60 m. OSC categorizes Sultanate of Oman into two zones; a high seismic zone (Zone-1) and a low seismic zone (Zone-2). Muscat the capital of the country falls in Zone-1. According to UBC, Muscat falls in Zone-2A, this definition was used as the reference for zonal equivalence. The paper compares base shear and lateral force distribution obtained from the three seismic codes using equivalent static load method. 4-, 10and 14storey buildings having heights of 17 m, 41 m and 57 m, respectively were considered. The buildings were modeled as reinforced concrete having normal occupancy conditions, resting on soil class “C” defined as very dense soil or soft rock. Both zones of OSC were used for comparison. For all b...

Application of NEHRP classification to AVS30 obtained from microtremor array measurement in Muscat, Oman

Seismic Liquefaction Potential in Muscat, Sultanate of Oman

Journal of Earth Science & Climatic Change

Seismic liquefaction is a serious geotechnical engineering problem that takes place in saturated ... more Seismic liquefaction is a serious geotechnical engineering problem that takes place in saturated cohesion less soils during earthquakes due to the increase of pore-pressure so that the soil shear strength is decreased to zero. Muscat is situated in the north-eastern part of Oman close to Oman Mountains, which witnessed four earthquakes of order of 5.2 magnitude in the last 1300 years. The surface geology of Muscat reveals great variety of hard rocks in the eastern, southern and western parts to dense and lose sediments in the middle and northern parts. Muscat Municipality provided 1082 borehole data to be examined for their liquefaction susceptibility based on the soil characteristics. Susceptible soils only are further considered to liquefaction hazard assessment. Liquefaction occurs during an earthquake if the cyclic stress ratio (CSR) caused by the earthquake is higher than the cyclic resistance ratio (CRR) of the soil. CSR values were evaluated using probabilistic peak ground acceleration (PGA) values for return period of 2475 years at the surface given by detailed hazard and micro zonation studies. CRR for Muscat region is conducted based on the borehole data with N values of SPT tests, and shear wave velocity results from 99 MASW surveys over the entire region. All the required corrections to get standardized (N1) 60 values, to correct shear-wave velocity, and scale the results for Mw 6.0 instead of the proposed 7.5 are conducted. Liquefaction hazard maps were created using the minimum factor of safety (FS) at each site as a representative of the FS against liquefaction at that location. Results indicate that under the current level of seismic hazard, liquefaction potential is possible at some sites along the northern coast, where alluvial soils, shallow ground water table, and relatively high ground motion are present. The expected settlement of the soft soil at each liquefiable site is also evaluated.

Moment Magnitudes of Local/Regional Events from 1D Coda Calibrations in the Broader Middle East Region

Bulletin of the Seismological Society of America, 2016

Short-period body wave and long-period surface wave magnitudes are important for event characteri... more Short-period body wave and long-period surface wave magnitudes are important for event characterization, and yield estimation applications. However, the uneven distribution of stations, complex heterogeneous structure, and high attenuation of the Middle East make it difficult to calculate these magnitudes using simple 1-D path corrections. While reliable 1-D long-period regional moment magnitudes are routinely computed for the larger magnitude events, oftentimes the smaller events do not have the required bandwidth and are thus not suitable for long-period waveform modeling that require periods of 5 seconds or greater. The complex structure of the lithosphere in the region causes significant variation in the recorded amplitude of body and surface waves that travel along different paths, as well as phase blockage. These strong 2-D effects are most significant for source characterization of small and moderate magnitude events, which are often only observable at periods of less than 2 seconds. While the regional coda envelope method for moment magnitude estimation [22] has proven to be very robust in many studies, they still require 2-D path corrections for the shorter periods in laterally complex regions Iranian and Turkish Plateaus. This current study will provide the necessary 1-D initial starting model for use in a future 2-D coda study. We are also very fortunate to have access to many new broadband stations that have become available in the region, through improved national networks as well as temporary deployments. This has given us the opportunity to make thousands of coda amplitude measurements to calculate source parameters, specifically we have estimated the source moment-rate spectra and moment magnitudes for roughly 2,900 events recorded by 74 stations over 13 narrow frequency bands ranging between 0.03-8 Hz. Moreover, this data will be crucial for 2-D path corrections for coda in the future. The absolute scaling of these spectra was calculated based on an independent waveform modeling solutions of the moment magnitudes for a subset of these events to avoid circularity. Using our1-D path calibrations, we obtain fairly good agreement with waveform-modeled seismic moments for the larger events (Mw > 4.5), for the low frequencies (< 0.7 Hz). As expected, the coda-derived source spectra become very scattered at higher frequencies (>0.7-Hz) because of uncorrected 2-D path effects as well as mixing of both Sn-coda and Lg-coda which are likely to have different attenuation.

Site-specific earthquake ground motion parameters at the southeastern part of Muscat, Sultanate of Oman

Journal of African Earth Sciences

Abstract The site-specific earthquake ground motion parameters were presented for the southeaster... more Abstract The site-specific earthquake ground motion parameters were presented for the southeastern part of Muscat governorate, including amplification factor at different periods and the values of PGA and spectral accelerations at the surface. The study starts with assessment of the seismic hazard at bedrock level using the probabilistic approach. This assessment was preformed considering an updated earthquake catalogue . The outputs of the probabilistic seismic hazard were uniform hazard spectra for return periods of 475,975 and 2475 years. Spectral matching technique was applied to define the compatible ground motion time series based on the outputs of the probabilistic approach and the deaggregation process. The representative's dynamic soil profiles were determined using the in-situ measurements of compressional and shear waves. The effects of soil deposits on the propagated ground motions time series was evaluated using the equivalent linear analysis in the frequency domain. The final results clarified that, the fundamental site period at the middle coastal parts of the area has the largest values (0.2–0.276 s). The maximum amplification factors found to be 2.76, 2.36, and 2.8 for the periods of PGA, 0.1 s, and 0.2 s, respectively. The values of PGA and spectral accelerations at the surface level are also provided.

Compiling an earthquake catalogue for the Arabian Plate, Western Asia

Journal of Asian Earth Sciences

Integrated GPR, ERT and MASW for detecting near‐surface caverns at Duqm area, Sultanate of Oman

Near Surface Geophysics

Probabilistic and deterministic estimates of near-field tsunami hazards in northeast Oman

Geoscience Letters

Tsunamis generated along the Makran subduction zone (MSZ) threaten the Sur coast of Oman, accordi... more Tsunamis generated along the Makran subduction zone (MSZ) threaten the Sur coast of Oman, according to deterministic and probabilistic analyses presented here. A validated shallow water numerical code simulates the sourceto-coast propagation and quantifies the coastal hazard in terms of maximum water level, flow depth, and inundation distance. The worst-case source assumed for the eastern MSZ is a thrust earthquake of Mw 8.8. This deterministic scenario produces simulated wave heights reaching 2.5 m on the Sur coast leading to limited coastal inundation extent. Because Oman adjoins the western MSZ, the probabilistic analysis includes the effect of this segment also. The probabilistic analysis shows onshore inundations exceeding 0.4 km northwest of Sur where flow depths are likely to exceed 1 m in 500 years. Probability analysis shows lesser inundation areas with probability of exceeding 1 m flow depth up to 80% in 500-year exposure time. Teletsunamis are excluded from these analyses because far-field waves of the 2004 Indian Ocean tsunami did not impact the Sur coast. Also excluded for simplicity are tsunamis generated by submarine slides within or near MSZ rupture areas. The results of this research provide essential information for coastal planning, engineering and management in terms of tsunami hazard and an essential step toward tsunami risk reductions in the northwest Indian Ocean.

Probabilistic Seismic Hazard Assessment for the Arabian Peninsula

Pure and Applied Geophysics

Developing a seismic source model for the Arabian Plate

Arabian Journal of Geosciences

Near-surface site characterization at Quriyat City, Sultanate of Oman using HVSR and MASW techniques

Arabian Journal of Geosciences, 2015

COOL: Crust of the Oman Ophiolite and its Lithosphere-a passive seismic experiment